Adjustments - Carrier 58STA Installation, Start-Up, Operating And Service And Maintenance Instructions

ELECTRICAL SHOCK HAZARD
Failure to follow this warning could result in electrical shock,
personal injury, or death.
Blower access door switch opens 115-v power to control. No
component operation can occur unless switch is closed.
Caution must be taken when manually closing this switch for
service purposes.
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3. To Begin Component Self-Test:
Remove blower access door. Disconnect the thermostat R lead
from furnace control board. Manually close the blower door
switch. Short (jumper) the C
TEST/TWIN 3/16-inch quick connect terminal on control
until LED goes out (approximately 2 sec). Gas valve and
humidifier will not be turned on. (See Fig. 24.)
NOTE: The furnace control allows all components, except the gas
valve, to be run for short period of time. This feature helps
diagnose a system problem in case of a component failure.
Component test feature will not operate if any thermostat signal is
present at the control.
Component test sequence is as follows:
Refer to service label attached to furnace or see Fig. 49.
a. LED will display previous status code 4 times.
b. Inducer motor starts and continues to run until Step f of
component test sequence.
c. Hot surface igniter is energized for 15 sec., then off.
d. Blower motor operates on HEAT speed for 10 sec.
e. Blower motor operates on COOL speed for 10 sec.
f. Inducer motor stops.
g. Reconnect R lead to furnace control board, release blower
door switch and re-install blower door.
4. Operate furnace per instruction on door.
5. Verify furnace shut down by lowering thermostat setting
below room temperature.
6. Verify furnace restarts by raising thermostat setting above
room temperature.
Step 3—Adjustments
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FIRE HAZARD
Failure to follow this warning could result in reduced furnace
life, property damage, injury and death.
DO NOT bottom out gas valve regulator adjusting screw.
This can result in unregulated manifold pressure and result in
excess overfire and heat exchanger failures.
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FURNACE DAMAGE HAZARD
Failure to follow this caution may result in reduced furnace
life.
DO NOT redrill orifices. Improper drilling (burrs, out-of-
round holes, etc.) can cause excessive burner noise and
misdirection of burner flames. This can result in flame
impingement of heat exchangers, causing failures. (See Fig.
47.)
Furnace gas input rate on rating plate is for installations at altitudes
up to 2000 ft. Furnace input rate must be within ±2 percent of
furnace rating plate input.
-24V terminal on control to the
OM
1. Determine the correct gas input rate.
In the U.S.A.:
The input rating for altitudes above 2,000 ft. must be reduced
by 4 percent for each 1,000 ft. above sea level. For installa-
tions below 2000 ft., refer to the unit rating plate. For
installations above 2000 ft., multiply the input on the rating
plate by the de-rate multiplier in Table 8 for the correct input
rate.
In Canada:
The input rating must be derated by 10 percent for altitudes of
2,000 ft. to 4,500 ft. above sea level by an authorized Gas
Conversion Station or Dealer. To determine correct input rate
for altitude, see example 1 and use 0.90 as derate multiplier
factor.
EXAMPLE 1:
88,000 BTUH INPUT FURNACE INSTALLED AT 4300 FT.
Furnace Input Rate
at Sea Level
88,000
2. Determine the correct orifice and manifold pressure adjust-
ment. There are two different orifice and manifold adjustment
tables. All models in all positions, except Low NOx models in
downflow or horizontal positions, use Table 12 (22,000
BTUH/Burner)
Low NOx models in the downflow or horizontal positions
must use Table 13 (21,000 BTUH/Burner). See input listed on
rating plate.
a. Obtain average yearly gas heat value (at installed altitude)
from local gas supplier.
b. Obtain average yearly gas specific gravity from local gas
supplier.
c. Find installation altitude in Table 12 or 13.
d. Find closest natural gas heat value and specific gravity in
Table 12 or 13.
e. Follow heat value and specific gravity lines to point of
intersection to find orifice size and manifold pressure
settings for proper operation.
f. Check and verify burner orifice size in furnace. NEVER
ASSUME ORIFICE SIZE. ALWAYS CHECK AND
VERIFY.
g. Replace orifice with correct size if required by Table 12 or
13. Use only factory-supplied orifices. See EXAMPLE 2.
For 22,000 BTUH burner applications use Table 12
EXAMPLE 2: (0–2000 ft altitude)
Heating value = 1000 Btu/cu ft
Specific gravity = 0.62
Therefore: Orifice No. 43*
Manifold pressure: 3.7-in. wc
* Furnace is shipped with No. 43 orifices. In this example
all main burner orifices are the correct size and do not need
to be changed to obtain proper input rate.
3. Adjust manifold pressure to obtain correct input rate.
a. Turn gas valve ON/OFF switch to OFF.
b. Remove manifold pressure tap plug from gas valve. (See
Fig. 46.)
c. Connect a water column manometer or similar device to
manifold pressure tap.
d. Turn gas valve ON/OFF switch to ON.
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e. Manually close blower door switch.
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Derate Furnace Input Rate
X Multiplier = at Installation
Factor Altitude
X 0.90 = 79,200